Bananas are a popular fruit, but they often spoil quickly, leading to waste. Katherine McPhillips learned that bananas emit ethylene gas, which accelerates ripening, especially when stored with other fruits. To combat this, she stopped placing bananas in a fruit bowl and instead put them on a plate away from heat sources. By covering the stems of the bananas with tin foil, she found that their freshness could last up to 14 days. This method is effective because it slows the release of ethylene gas, which is primarily emitted from the stems. Katherine's approach has not only kept her bananas vibrant yellow but also helped her save money by reducing food waste. In contrast, other coverings like cling film can trap moisture and baking paper is not airtight, making tin foil the best choice for maintaining banana freshness. This simple technique requires just 30 seconds of effort and has significantly cut down on her grocery bills.